1. Field of the Invention
This invention relates generally to solar power control systems, and in particular, to an efficient system and method for applying solar-generated power to refrigeration.
2. Description of the Related Art
Two billion people live without electricity. They represent a market for various solar powered systems such as stand-alone power systems and small capacity solar refrigerators. Efforts have been made to develop stand-alone photo voltaic (PV) power systems that provide lighting and power for small devices such as radios and small televisions. For example, such systems may include a solar panel, a battery, and a low wattage fluorescent light. Solar refrigerators, however, represent a bigger challenge.
Previous attempts to produce a marketable solar refrigerator have been largely unsuccessful. For example, consider the following patents:
In U.S. Pat. No. 4,126,014, Thomas Kay discloses an absorption refrigeration system powered by a heated fluid from a solar panel. PA0 In U.S. Pat. No. 5,501,083, Tae Kim discloses an AC-powered air conditioner having a solar panel for backup electrical power. PA0 In U.S. Pat. No. 5,497,629, Alexander Rafalovich discloses the use of solar power in an air conditioning system to pump heat from an indoor space to a thermal store. PA0 In U.S. Pat. No. 5,685,152, Jeffrey Sterling discloses using a heated medium from solar collectors to produce a cold thermal store and mechanical energy to pump heat from an indoor space to the cold thermal store.
Kay's refrigeration system provides no means to maintain refrigerator operation in the absence of sunlight (e.g. at nighttime or on overcast days). As the air conditioning systems are largely unsuited for even small capacity refrigerators or freezers, no attempt has been made to scale these systems to produce a commercializable solar refrigerator.
Accordingly, it is desirable to provide an efficient, inexpensive, commercializable small capacity solar refrigerator which can operate for several days in the absence of sunlight. As batteries are often expensive and require regular maintenance, it would further be desirable to provide such a solar refrigerator which does not require batteries.